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Misc - Congenital, zoonotic, arbo viruses

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Virology

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Misc - Congenital, zoonotic, arbo viruses

  1. 1. Congenital Viral Infections
  2. 2. Congenital, Perinatal, and Neonatal Viral Infections Intrauterine • Rubella • CMV • HSV • VZV • HIV • HTLV-1 • Hepatitis B • Hepatitis C • Parvovirus B19 • Lassa Fever • Japanese Encephalitis Perinatal and Neonatal • HSV • VZV • HIV • HTLV-1 • Hepatitis B • Hepatitis C
  3. 3. Arthropod-borne Viruses (Arboviruses) Are viruses that can be transmitted to man by arthropod vectors
  4. 4. Arthropod Vectors Mosquitoes Dengue, yellow fever Ticks Crimean-Congo haemorrhagic fever Sandflies Rift valley fever
  5. 5. Examples of Arthropod Vectors Phlebotmine SandflyCulex Mosquito Assorted TicksAedes Aegypti
  6. 6. Dengue Fever • The biggest arbovirus problem in the world today with over 2 million cases per year • Dengue is found in SE Asia, Africa and S America. • Transmitted by Aedes mosquitoes residing in water-filled containers. • Transmission cycle: human-mosquitoe-human
  7. 7. Distribution of Dengue
  8. 8. • High fever, lymphadenopathy, myalgia, bone and joint pains, headache, and a maculopapular rash. • Severe cases may present with haemorrhagic fever and shock with a mortality of 5-10%. (Dengue haemorrhagic fever or Dengue shock syndrome) Dengue Fever
  9. 9. Dengue Haemorrhagic Fever
  10. 10. Dengue Fever • Diagnosis : by serology. • Treatment: no specific antiviral therapy. • Prevention  Mosquito eradication.  Removal of all containers from premises which may serve as vessels for egg deposition.  A live attenuated vaccine is being tried in Thailand with encouraging results.
  11. 11. Viral Zoonosis
  12. 12. Rabies Virus Structure of rabies virus (CDC) • Characteristic bullet-shaped appearance • ssRNA enveloped virus
  13. 13. Epidemiology • Rabies is a zoonosis which is prevalent in wildlife. • The animals involved differ from continent to continent. • Wide range of hosts: fox, bats wolf dog
  14. 14. Rabies: Pathogenesis Rabid animals become aggressive and harbor the virus in saliva
  15. 15. Rabies: Clinical Features • Incubation Period depends on:  Infective dose  Site of animal bite • Prodromal Period (up to two weeks)  Pain or itching at the site of the wound,  Fever & headache. • CNS infection (Neurological phase)  Hydrophobia in half of the patients.  Seizures and hallucinations.  Paralysis leading to respiratory failure  Coma & death
  16. 16. Laboratory Diagnosis Histopathology (Negri Bodies) • Are pathognomonic of rabies • Are intracytoplasmic inclusions formed by aggregates of nucleocapsids in neurons of about 90% of infected humans Negri Body in neuron cell (CDC)
  17. 17. Rapid virus antigen detection Positive DFA test (CDC Laboratory Diagnosis Virus Cultivation Serology
  18. 18. Management and Prevention Pre-exposure Prophylaxis • Inactivated rabies vaccine to high risk persons like vets, animal handlers, laboratory workers etc. Post-exposure Prophylaxis • In cases of animal bites, dogs and cats in a rabies endemic area should be held for 10 days for observation. If signs develop, they should be killed and their tissue examined. • Local treatment of wounds • Passive immunization - human rabies immunoglobulin • Active immunization - the human diploid cell vaccine is usually administered into the deltoid region, and 5 doses are usually given.
  19. 19. Established Rabies • Nothing much can be done except intensive supportive care. • To date, only 2 persons with proven rabies have survived. Management and Prevention
  20. 20. Control of Rabies • Urban - canine rabies: 99% of all human rabies. – Dog control – Vaccination of dogs – Quarantine of imported animals • Wildlife - much more difficult to control.
  21. 21. • G Protein (Surface glycoprotein) – Binds to cellular receptors and is the target of neutralizing antibodies • M (matrix) protein. – This is a peripheral membrane protein may act as a bridge between the membrane or G protein and the nucleocapsid. • N (Nucleoprotein) protein – This is the major structural protein that covers the RNA genome and protects it from nucleases. • L (Large) protein – Its gene takes up 60% of the genome • P (phospho)) protein Rabies Virus Proteins

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